Five-0 enlists the help of a Californian ATF Agent to find a serial arsonist targeting couples on Oahu. Meanwhile, when Danny whisks Amber away for a romantic getaway, her abusive ex-husband tracks them down, intent on taking his wife back.

Hawaii Five-0‘s 100th episode was a turning point for the show in more ways than one. In addition to hitting the milestone, the hour ended with the shocking death of Wo Fat (Mark Dacascos), the character who’s been the nemesis of Steve McGarrett (Alex O’Loughlin) dating back to the original series.

And make no mistake — Wo Fat is definitely, definitely dead, assures executive producer Peter Lenkov. “It’s not one of those, I was wearing a Kevlar vest, or you didn’t see me after the camera left. I got up. I’m still breathing,” Lenkov tells TVGuide.com. “He’s dead. He’s got a bullet in his head and there’s no coming back from that.”

When McGarrett is kidnapped by Wo Fat, he experiences various realities. While his team searches for him, Steve is interrogated by Wo Fat and subjected to drugs that cause him to hallucinate; if perhaps his and his friend’s life had taken a different path.